There is an increasing desire for electric grills. This is particularly true because the urban population is expanding. Many urban or other environments may not easily permit the use of traditional gas or charcoal grills. For example, many urban dwellers live in apartments or condominiums having balconies where they would like to use a grill. Because of smoke, gas or other concerns, use of typical charcoal or gas grills may not be permitted or desirable.
There are a number of available electric cooking devices, such as the George Foreman plate Grill (and similar devices), panini presses, electric griddles and the like. However, these prior art electric cooking devices are typically intended for indoor use and are not designed or constructed for use in harsh or caustic environments where they may be degraded by high heat, weather conditions such as sun and rain, as well as fats from foods or acids from cleaning agents. These harsh conditions may cause the electrical components to degrade, which in turn may lead to electrical current leakage or other unsafe conditions.
Because prior art electric cooking devices are generally intended for indoor environments, a typical wall outlet's current protection scheme is generally sufficient for these devices. Such devices may also rely on a ground line for protection. Some prior art circuits include metal-oxide-semiconductor field-effect transistors (MOSFETs) to regulate current. Yet other prior art circuits are thermally-responsive. However, there is a need for advanced protection circuitry in an electric grill that can respond to the failure of components, including but not limited to those which cause improper current conditions, such as those that may be found in or caused by harsh environments.
For example, U.S. Pat. No. 8,263,911, entitled “Electronic Device with Heating Protection Circuit and Heating Protection Method Thereof,” discloses an electronic device in which a control signal generated by a control module can assist the heating protection circuit in correctly determining whether a heating signal is failed or whether a control voltage of a control element is abnormal, and then automatically control the heating module to stop heating. The heating protection circuit uses a MOSFET coupled with a control module and a heating switch module. By contrast, some embodiments of the present invention use a combination of electro-mechanical and digital logic to detect multiple different types of failure conditions that simply cannot be detected by a MOSFET heating protection circuit.
Other prior art devices, referred to as thermally-responsive circuits, may shut down when a heating element reaches a threshold temperature. For example, U.S. Pat. No. 8,097,835, entitled “Temperature Control Circuit,” discloses a temperature detecting module which detects the temperature of the electronic device for outputting a detection signal to a protection module and microprocessors. The protection module controls the status of the microprocessor. But such thermally responsive circuits are inadequate for harsh environments and current conditions which may lead to component failures. In fact, failed components may lead to current leakage which does not always correlate with an overheated heating element. Dangerous current conditions may occur even if a heating element is within normal temperatures.
Thus, there is a need for an electric grill, including a grill with one or more independently controlled heating elements, having protection circuitry that protects against, among others things, short circuits, overcurrent, driver failure and/or microcontroller failure.